Watch out world, internet's grumpiest cat has hit her terrible twos

The top dog in Internet cat stardom, known for her downward smile and bugged-out baby blues, spent her birthday Friday touring New York City with an entourage worthy of Hollywood.

And Hollywood is where the funny-looking feline is bound, with a movie project in the works to add to her pile of endorsements and licensing deals that include her scowling face on limited-edition bags of Friskies Party Mix treats and her own line of "Grumppuccino" bottled coffee drinks.

Known for her facial expression, her owner Tabatha Bundesen says that Grumpy Cat's permanently grumpy-looking face is due to feline dwarfism. (AP photo)

So who will voice the cat we love to caption? Grumpy's not saying, nor are her humans, the brother-sister team of Tabatha and Bryan Bundesen.

With her own agent, YouTube videos that have racked up millions of hits, T-shirts, calendars and a best-selling book available in 14 languages, exactly how much is this cat worth?

"The business is doing very well," Bryan laughed. "Grumpy doesn't like to discuss specifics."

The humans, to be sure, are more than a little grateful.

Bryan Bundesen, left and his sister Tabatha Bundesen pose with Grumpy Cat as they prepare for an interview. (AP photo)

"We both were blue-collar people," Bryan said - he a cable company lineman in Ohio and she a server at a Red Lobster near her home in Morristown, Ariz. "It has changed our lives. It's been a blessing. We're very thankful for it."

The grump's real name is Tardar Sauce, so dubbed (and misspelled) by Tabatha's now 12-year-old daughter, Chyrstal, soon after their female pet calico gave birth to her and three siblings. The cat was tiny and is still petite, a victim of feline dwarfism, and wobbles a bit when she walks due to elongated rear legs that have only added to her popularity.

"She looks like a snowshoe Siamese is what we're told most," Bryan offers. "We've had some nice comments from people about it being nice that the spotlight's on a cat that's unique and has feline dwarfism. A lot of people are happy that it kind of spreads the message that it's OK to be different. She's also such a happy cat."

Grumpy is happy and extremely chill, with a reputation for falling asleep during interviews and seeking out dark corners to hide in.

If it hadn't been for Bryan slapping her photos on Reddit in late 2012, then following up with videos after their authenticity was questioned, Tardar might never have become a phenom.

"People said her face was Photoshopped," he said, so they took to YouTube to prove otherwise, earning about 1.5 million views overnight.

Now, Grumpy's YouTube channel has over 25 million views and 200,000 subscribers, with some wondering in comment threads whether the cat's calmness might be of the medicinal variety.

"It is absolutely unheard of to even think of drugging this kitty," Tabatha debunked.

Grumpy Cat walks on a table during a television interview. (AP photo)

While Grumpy has cashed in on Internet stardom, the field is far more crowded today. Any up-and-comers she has her eye on?

"There are a lot of cats on the Internet but there's no competition," a good-natured Bryan said. "She has the grumpy market cornered. All the other cats can have the happy, funny stuff."